试述椎动脉型颈椎病的病因及临床表现。
胸背神经支配()脊神经后支支配()副神经支配() ["A．竖脊肌","B．前锯肌","C．背阔肌","D．菱形肌","E．斜方肌"]
黄韧带的颈段()黄韧带的胸段()黄韧带的腰段() ["A．薄而窄","B．薄且宽","C．窄且稍薄","D．窄且稍厚","E．最厚"]
PAI
骶管裂孔平()两髂后上棘连线平()两侧髂嵴最高点的连线平() ["A．第3腰椎棘突","B．第4腰椎棘突","C．第5腰椎棘突","D．第2骶椎棘突","E．第4～5骶椎"]
外激活途径
